Device for facilitating transmission shifting

ABSTRACT

A shifting apparatus for a vehicle transmission having a multiplicity of sets of gears, operator-controlled means to change the speed of rotation of the transmission countershaft prior to the completion of a gear shift operation, an electrical circuit actuated by the operator for actuating the operatorcontrolled means, and a device responsive to the speed of the countershaft to exercise control over the electrical circuit whereby a desired speed relationship may be established between the countershaft and related rotating parts prior to completion of a gear-shifting operation.

United States Patent Irvin G. Detra Mertztown, Pa.;

Patrick J. Crowley, Hagerstown, Md. 827,368

May 23, 1969 June 1, l 97 l Mack Trucks, Inc.

Allentown, Pa.

Inventors Appl. No. Filed Patented Assignee DEVICE FOR FACILITATING TRANSMISSION SIIIFIING 6 Claims, 8 Drawing Figs.

U.S. Cl 74/339 Int. Fl6h 3/38 Field of Search 74/339;

References Cited UNITED STATES PATENTS 3,103,826 9/1963 Jaeschke 74/339 3,248,962 5/1966 McNamara et a1. 74/339 3,478,851 11/1969 Smyth et al. 74/339 FOREIGN PATENTS 611,512 12/1960 Canada 74/339 Primary ExaminerC. J. Husar Attorney-Brumbaugh, Graves, Donohue and Raymond ABSTRACT: A shifting apparatus for a vehicle transmission having a multiplicity of sets of gears, operator-controlled means to change the speed of rotation of the transmission countershaft prior to the completion of a gear shift operation, an electrical circuit actuated by the operator for actuating the operator-controlled means, and a device responsive to the speed of the countershaft to exercise control over the electrical circuit whereby a desired speed relationship may be established between the countershaft and related rotating parts prior to completion of a gear-shifting operation.

PATENTED JUH 1 |97| SHiU 1 UF 5 INVHN'IUAS IRVIN G. DETRA 8| PATRICK J. CROWLEY their ATTORNEYS PAIENTEU JUN H971 3.581.590

SHEET 2 OF 5 INVEN'I'URS IRVIN G. DETRA 8 BY PATRICK J. CROWLEY BMM MUW their ATTORNEYS PATENTED JUN 1 197i SHEET 3 0F 5 m EM INVliNI'URS mvm s. DETRA a PATRICK J. CROWLEY BY WM, AIL-,IL7 J their nrromvsrs PATENTEI] JUN 1 197i 3.581.590

' SHEET u 0F 5 INVIL'N'IURS IRVIN G. DETRA 8 BY PATRICK J. CROWLEY Law/. 1 aw, 1 mg; p mp their ATTORNEYS PATENTEDJUN H9?! v BATTERY SHEET 5 [1F 5 INVIJN'IUAS IRVIN G. DETRA 8 BY PATRICK J. CROWLEY [QM A UNA M their ATTORNEYS DEVICE FOR FACILITATING TRANSMISSION SIIIFTING The present invention relates to mechanism for use with vehicle transmission devices in which the speed relationship between engageable transmission elements may be controlled or changed to facilitate the engagement of the transmission elements. Devices have heretofore been provided wherein this speed relationship may be controlled by means of speedsynchronizing devices consisting of balk mechanisms and relatively rotating friction elements to bring the interengaging parts into synchronous speed prior to the completion of the shift, a synchronizing mechanism being provided for each gear set, thus requiring considerable space and adding substantially to the cost of thevehicle transmission.

It is an object of the present invention to provide a mechanism capable of establishing a desired speed relationship between the relatively rotating parts of a vehicle transmission or gear box without the use of the aforesaid balk mechanisms and in such fashion that the time required to bring the engaging members into a desired speed relationship is relatively short and the operation may be accomplished without requiring a highly developed skill or sense of timing on the part of the operator. Furthermore, there is only one synchronizing mechanism for upshifting and a second synchronizing mechanism for downshifting, regardless of the number of gear sets in the transmission, thus providing a relatively simple and inexpensive transmission.

The invention will be particularly useful in connection with vehicle transmissions wherein the steps of the transmission are relatively widely spaced and substantially even intervals exist between the gear ratios as is the case when these transmissions are utilized in a power train having a prime mover capable of developing a substantially constant horsepower output over a wide operating range and the engine is operating within a given speed range throughout the aforesaid even intervals.

The foregoing object of the invention is attained by the provision of friction mechanism operable to vary the speed of rotation of the countershaft of the transmission mechanism and means responsive to the speed of rotation of the countershaft to control the operation of the friction means, this last-named means including an electrical circuit which is also controlled by the operator during shifting operations.

In accordance with a further object of the invention, the shifting of the gears of the transmission is accomplished not only during acceleration of the vehicle but deceleration thereof so that the speed of rotation of the transmission countershaft may be slowed or accelerated depending upon whether an upshift or a downshift operation, respectively, is performed.

In order that the invention may be more fully understood, reference will now be had to the accompanying drawings wherein:

FIG. I is a longitudinal view in section taken on a plane indicated by the line 1-1 in FIG. 2 and looking in the direction of the arrows, this view illustrating a vehicle transmission mechanism of the so-called clash-tooth type and wherein friction elements are provided for applying either a braking force to slow the transmission countershaft for upshifting or, for downshifting, a force to increase the speed of the transmission countershaft;

FIG. 2 is a view in transverse cross section taken on a broken plane indicated by the line 2-2 of FIG. I and looking in the direction of the arrows;

FIG. 3 is a plan view, partly broken away and in section, illustrating the transmission shifting mechanism, the section being taken on a plane indicated by the line 3-3 in FIG. I and looking in the direction of the arrows;

FIG. 4 is a partial view in longitudinal section taken on a plane indicated by the line 4-4 in FIG. 3 and looking in the direction of the arrows;

FIG. 5 is a partial view in longitudinal section taken on a plane indicated by the line 55 of FIG. 3 and looking in the direction of the arrows;

FIG. 6 is a partial plan view in section taken on a broken plane indicated by the line 6-6 of FIG. 1 and looking in the direction of the arrows, this view illustrating the shift pattern of the transmission;

FIG. 7 is a diagrammatic illustration of the electrical circuit and control elements for controlling the shifting operations of the transmission mechanism illustrated in FIG. 1 while making an upshift; and

FIG. 8 is a view similar to FIG. 7 illustrating a modified control circuit by means of which the transmission shifting may be effectively controlled and facilitated not only for upshifting operations but also for downshifting.

Referring to FIGS. I, 2 and 3, a conventional form of vehicle transmission is illustrated having a housing or gear box 10 in which there is journaled a driving shaft 11 and a coaxial driven shaft I2. These shafts are journaled in the end walls 13 and 14, respectively, of the gear box and the driven shaft is journaled in the drive shaft by means ofa bearing 15, all in accordance with known practice.

Also in accordance with standard practice, the gear box is provided with a plurality of countershafts 16 as shown in FIG. 2, only one of which is illustrated in FIG. 1. The countershafts 16 are driven from the drive shaft II by means of a driving gear 17 on the drive shaft and a plurality of driven gears 18 on the respective countershafts.

Between the countershafts 16 and the driven shaft 12, a plurality of sets of gears 19,119, 20, 20', 21 21', and 22, 22' are provided, corresponding to the first, second, third and fourth speed ratios, respectively, in accordance with standard practice. The fifth speed ratio is obtained by engaging the drive shaft 11 with the driven shaft 12 for direct drive.

As illustrated in FIG. I, the gears 20 and 21 are clutched to the driven shaft 12 by means of operator-controlled clutching mechanisms including a slidable sleeve 23 splined to the driven shaft 12 and having clutch teeth 24 and 25 for respectively engaging the mating clutch teeth of gears 20' and 21', while gear 19' is clutched to the driven shaft 12 and sleeve 23 by means of an outer sleeve 26 splined to the sleeve 23 and having clutch teeth 27 which engage mating clutch teeth on the gear 19. The drive shaft Ill and the gear 22' are clutched to the driven shaft 12 by means of another slidable sleeve 28 splined to the driven shaft I2 and having clutch teeth 29 and 30 for respectively engaging the mating clutch teeth of gears 17 and 22'.

Operation of the foregoing clutch mechanisms is accomplished by means of shifter rods 31,32 and 33 (FIG. 2), rod 31 carrying a shifter fork 34 for engaging the sleeve 28, rod 32 carrying a shifter fork 35 for engaging the inner sleeve 23, and rod 33 carrying a shifter fork 36 for engaging the outer sleeve 26.

The shifter rods 31, 32 and 33 are actuated by a shift lever 37 in accordance with standard practice, the lower end of this lever being formed with a shifter finger that engages notches in brackets carried by the respective shifter rods.

Also in accordance with standard practice, a reverse gear set is provided including a driving pinion 38 mounted on the countershaft 16, an idler pinion 39, and driven gear 40 slidably mounted upon the driven shaft. The driven gear is actuated by means of a shifter fork 41 mounted upon the shifter rod 33. 7

All of the foregoing mechanism including further details and variations thereof conforms with standard practice and forms no part of the present invention.

In accordance with the present invention, the countershaft I6 is provided with a brake mechanism 42 at one end thereof, as illustrated in FIG. 1. This mechanism includes a central spider or flanged member 43 which is secured to the countershaft by means of a bolt or the like 44. The outer periphery of the member 43 is splined at 45 and a plurality of brake discs 46 are slidably but nonrotatably secured to the splines 45. A housing 47 is secured to the end wall 14 and is provided with inwardly extending splines 48 within which are received stationary friction discs 49. These discs are interleaved between and lie upon outer sides of the friction discs 46 and are compressed against the discs 46 by means of an annular piston member 50 slidably received within the housing 47. A plurality of springs 51 normally urge the piston 50 to the left as viewed in FIG. 1 and thus prevent the application of force to the discs 49. In order that the friction discs may be forced to go into a brake-applying position, a fluid under pressure is supplied to an annular chamber 52 by means of a conduit 53, presently to be described in connection with the related parts of the control mechanism. From the foregoing, it will be seen that, when sufficient fluid pressure is supplied in the annular chamber 52, the piston 50 will be forced to the right as viewed in FIG. 1 to compress the friction discs and thus apply a braking force to the countershaft 16 and the drive shaft 11 connected thereto.

Referring to the diagrammatic illustration in FIG. 7, the conduit 53 is illustrated as supplying air under pressure to the annular cylinder 52 and related mechanism within the housing 47. The flow of air is controlled by a valve 54 actuated by a solenoid 55. The solenoid 55 is in an electrical circuit including a wire 56, a speed control switch 57, wire 58, switch 59 controlled by the transmission shift lever, wire 60, switch 61 actuated by a plunger 62 which in turn is operated by the clutch pedal of the vehicle, wire 63 and battery 64. The battery 64 and the solenoid 55 are both grounded so that, when switches 57, 59 and 61 are closed, the solenoid is actuated to deliver air to the cylinder 52 of the brake mechanism.

The speed control switch 57 is actuated by a mechanism indicated generally at 65 (see also FIG. 1) comprising a governor-controlled device which is driven by, and senses the speed of, the countershaft 16 as well as the drive shaft 11 engaged therewith. Thus, the movable element of the switch 57 is actuated by the mechanism 65 in response to the speeds of the countershaft and the drive shaft.

The switch 59 is closed when its spring-biased plunger 59a drops into a depression 67 formed in a pivoted arm 68 (see FIG. 4). The free end of the arm 68 is bifurcated and receives the shift lever 37 (see FIG. 3). The depression 67 extends over a sufficient area of the pivoted arm so that the switch is closed for any position of the gear shift lever in the neutral zone. Accordingly, the operation of the switch 59 will be performed merely by a longitudinal (that is, in a direction parallel to the movement of the shifter rods) motion of the gearshift lever in moving from one speed change position to another.

To enable the brake to be operated when the vehicle is standing still and a shift is to be made into first or reverse speeds, a governor bypass switch 69 is provided in a bypass circuit 70, the switch 69 being closed by a gear shift lever follower member 71, as illustrated in FIG. 5. The follower member slidably receives the shift lever 37 and is carried by a rod 72 slidably mounted to the transmission housing. The follower member is formed so as to permit relative motion between it and the shift lever when the latter displaces the shifter rods 31, 32 and 33, but movement of the shift lever perpendicular to the shifter rods displaces the follower member. The follower member 71 includes a pair of depending lugs 71a and 71b which are adapted to be received in the the brackets on the shifter rods 31, 32 and 33 to positively lock those shifter rods not engaged by the shift lever 37.

The operation of the mechanism is as follows. Assuming that the vehicle is at a standstill and the driven shaft 12 is not rotating, it will be seen that the engine and drive shift 11, as well as the countershaft 16, are rotating and that, in order to engage the gear set 19, 19' to establish the low (or to engage the gear set 38, 39, 40 to establish the reverse) gear relationship between the driving and driven shafts, it will be necessary to slow down the countershaft and the drive shaft by applying a braking force through the friction discs 46 and 49 by actuating the piston 50.

When the shift lever 37 is moved laterally to engage either the low or reverse gear set, the governor bypass switch 69 is closed by the follower member 71. Thus the solenoid circuit including wires 56, 70 and 60 is closed except for the clutch pedal operated switch 61. Thus, when the operator disengages the clutch by depressing the clutch pedal, the entire circuit is closed and the solenoid 55 energized to actuate the brake 42. This will slow down the countershaft and permit easy engagement of the selected gear set.

Shifting up from first to second and on to third, fourth and fifth speeds will utilize the governor switch 57 in the following manner. When the speed of the countershaft 16 is sufficiently high to require the actuation of the brake mechanism abovedescribed, the contacts of the switch 57 are closed, thus exerting a speed-responsive control over the circuit illustrated in FIG. 7. If, at this point, the clutch pedal is depressed to disengage the clutch, thus depressing the plunger 62 and closing the switch 61, the entire circuit is then completed when the shift lever 37 is moved into the neutral position, thereby closing the switch 59.

When the circuit is closed, the solenoid 55 is energized to open the valve 54 and permit air to enter the annular chamber 52 and thus force the annular piston 50 to the right as viewed in FIG. 1, compressing the brake discs and applying a braking force to the countershaft l6 and the drive shaft 11. The desired speed relationship between the countershaft 16 and the driven shaft 12 is attained prior to actual synchronization of the gears, and at that desired speed relationship the switch 57 is opened by the governor 65 and the solenoid 55 deenergized, causing the valve 54 to be closed and, at that time, the springs 51 release the pressure from the brake discs. The operator may then, by sliding the inner sleeve 23 to the right, as viewed in FIG. 1, clutch the gear 20 to the inner sleeve 23 and the driven shaft 12 to complete the shifting operation into second gear. Similar operations are performed in shifting into higher gears, the sleeve 23 being moved to the left to shift into third, while the sleeve 28 is moved to the right for fourth and to the left for fifth (direct drive).

It will thus be seen that the switch 59 prevents operation of the system except when the transmission is neutralized and that the clutch-controlled switch 61 prevents operation of the system when the clutch is engaged. Over these switches and the related circuits, the speed-controlled switch 57 exercises a control to assure the actuation of the brake at such times as the speed relationship between the countershaft 16 and the driven shaft 12 is such as to interfere with satisfactory engagement of the desired gear set. It is to be understood that the speed sensor or governor which operates the switch 57 operates to release the brake somewhat before the slowing parts reach a speed synchronous with the output shaft. For example, the brake might be released when the countershaft is rotating at a speed of 1,350 rpm. instead of 1,250, which would be the synchronous speed for the gear set. The operator may thus quickly proceed with the engagement of the next ratio with a minimum of hesitation and with very little or no clash and wear upon the gear sets.

In order to accomplish the desired control of the gear-shifting operation in downshifting, that is, when the shift is from a higher speed to a lower speed, a clutch mechanism is provided between the driven shaft and the countershaft. As illustrated in FIG. 1, the countershaft is provided with a gear 75 engaging a mating gear 76 journaled upon the driven shaft. Within the gear 76 there are provided a plurality of splines 77 carrying fiction discs 78 between which cooperating friction discs 79 are provided mounted upon splines 80 formed upon a clutch spider 81. The clutch spider is splined to the driven shaft 12 and is axially movable by means of a collar 82 journaled to the hub of the spider 81 by ball bearings 83. As will be seen in FIG. 2, a fork 84 is mounted upon the hub or collar 82 and is secured to a vertical shaft 85 by means of bolts 86. The upper end of shaft 85 is provided with a lever 87 that is actuated by a rod 88 which is operated by an air-controlled cylinder and valve mechanism 89.

When the fork 84 is moved to the left as viewed in FIG. 1, the spider 81 is similarly moved and the clutch plates 78 and 79 are compressed to cause the gear 76 to drive the gear 75. This results in speeding up the countershaft 16 (and the drive shaft 11) to bring it to a desired speed of rotation such that a desired downshift may be effected.

Turning to FIG. 8, the circuit for accomplishing this downshifting operation is illustrated as including not only the elements of FIG. 7 but certain additional elements, as follows.

Inasmuch as the governor or speed-responsive device is only responsive to speed, it is not able to sense when an operation is an upshift or a downshift operation. Accordingly, an operatorcontrolled selector switch 90 is provided on the gear shift lever 37. The movable switch member may be engaged with either of the stationary switch contacts 91 and 92 for selecting either an upshifting or a downshifting operation, respectively. If the movable contact of the switch 90 engages the contact 91, then the circuit though the wires 58 and 58a is closed and the connections are established for upshifting operations. On the other hand, if the stationary contact 92 is engaged, then the wire 58 is connected to a wire 93 which is connected to a second governor-controlled switch 94 that is, in turn, adapted to be connected to a fixed contact 95 which is connected to a wire 96 in the circuit of a solenoid 97. The solenoid 97 operates the valve 89 (illustrated in FIG. 2) to engage the f riction discs 78 and 79 and, as a result, to speed up the countershaft l6 and the drive shaft I] through the gears 75 and 76.

The governor-controlled switch 94 is opened to disengage the clutch plates 78 and 79 preferably somewhat after the accelerating parts reach a speed synchronous with the output shaft. Accordingly, the governor-controlled switches 57 and 94 are actuated at different countershaft speeds by the governor 65a, the switch"57 being closed at a speed above, and the switch 94 at a speed below, the corresponding synchronous speed of the countershaft, while each of the switches is opened at a speed above such synchronous speed.

It will be seen that the downshifting operations are accomplished by first selecting the downshifting position of the switch 90 on the shift lever 37 and then disengaging the clutch and shifting the gearshifting lever into the neutral position in order that both switches 61 and 59 may be closed to permit the operation of the governor-controlled switch 94 to engage the clutch 78, 79 and speed up the countershaft to facilitate easy shifting.

The above-described embodiments of the invention are intended to be merely exemplary, and those skilled in the art will be able to make numerous variations and modifications of them without departing from the spirit and scope of the invention. For example, the brake mechanism could be disposed so as to act directly on the drive shaft by being coupled to the driving gear 17, since the drive shaft and the countershaft are always engaged. Similarly, the governor may be mounted so that it is driven by the drive shaft. Also, one or more fluidic devices may be substituted for the above-described electrical devices to accomplish the sensing, switching and actuating functions of the electrical control circuit, thereby providing a fluidic control system or an electric-fluidic hybrid system.

We claim:

l. A vehicle transmission mechanism having a driving shaft, a driven shaft, a countershaft driven by the driving shaft, sets of gears between the countershaft and one of the other shafts, friction means operable to vary the speed of rotation of the countershaft, and means responsive to the speed of rotation of the countershaft to control the operation of the friction means, the means to control the friction means comprising an electrical circuit, means actuated by the circuit to operate the friction means, a switch in the circuit and operating mechanism therefor responsive to the speed of the countershaft, switches in the circuit operated by the vehicle clutch pedal and gearshifting mechanism respectively, and a switch in the circuit to bypass the speed responsive switch.

2. A vehicle transmission mechanism having a driving shaft, a driven shaft, a countershaft driven by the driving shaft, sets of gears between the countershaft and one of the other shafts, friction means operable to vary the speed of rotation of the countershaft, and means responsive to the speed of rotation of the countershaft to control the operation of the friction means, the friction means including brake mechanism and ac tuatin means therefor to apply a braking force to the countersha tand a clutch mechanism between the driven shaft and countershaft and actuating means therefor to increase the speed of the countershaft by the driven shaft.

3. Transmission mechanism according to claim 2 wherein the means to control the operation of the friction means comprises a control circuit which includes a manually operated switch to select the operation of the brake or the clutch.

4. Transmission mechanism according to claim 2 wherein the means to control the operation of the friction means comprises a control circuit which includes two switches actuated by the speed responsive means, one connected to the brakeactuating means and one to the clutch-actuating means, and a manually operated switch to select either of the two lastnamed switches.

5 A vehicle transmission mechanism having a driving shaft, a driven shaft, a countershaft driven by the driving shaft, sets of gears between the countershaft and one of the other shafts, braking means for applying a braking force to the countershaft, means responsive to the speed of rotation of the countershaft to control the operation of the barking means comprising a control circuit, means actuated by the circuit to operate the braking means, first switch means in the circuit, means responsive to the speed of the countershaft to actuate the first switch means, and second switch means in the circuit for bypassing the first switch means.

6. Transmission mechanism according to claim 5 including means responsive to the gearshifting mechanism of the transmission for actuating the second switch means to bypass the first switch means when a gear set is to be engaged in order to move the vehicle from a standstill position. 

1. A vehicle transmission mechanism having a driving shaft, a driven shaft, a countershaft driven by the driving shaft, sets of gears between the countershaft and one of the other shafts, friction means operable to vary the speed of rotation of the countershaft, and means responsive to the speed of rotation of the countershaft to control the operation of the friction means, the means to control the friction means comprising an electrical circuit, means actuated by the circuit to operate the friction means, a switch in the circuit and operating mechanism therefor responsive to the speed of the countershaft, switches in the circuit operated by the vehicle clutch pedal and gearshifting mechanism respectively, and a switch in the circuit to bypass the speed responsive switch.
 2. A vehicle transmission mechanism having a driving shaft, a driven shaft, a countershaft driven by the driving shaft, sets of gears between the countershaft and one of the other shafts, friction means operable to vary the speed of rotation of the countershaft, and means responsive to the speed of rotation of the countershaft to control the operation of the friction means, the friction means including brake mechanism and actuating means therefor to apply a braking force to the countershaft and a clutch mechanism between the driven shaft and countershaft and actuating means therefor to increase the speed of the countershaft by the driven shaft.
 3. Transmission mechanism according to claim 2 wherein the means to control the operation of the friction means comprises a control circuit which includes a manually operated switch to select the operation of the brake or the clutch.
 4. Transmission mechanism according to claim 2 wherein the means to control the operation of the friction means comprises a control circuit which includes two switches actuated by the speed responsive means, one connected to the brake-actuating means and one to the clutch-actuating means, and a manually operated switch to select either of the two last-named switches. 5 A vehicle transmission mechanism having a driving shaft, a driven shaft, a countershaft driven by the driving shaft, sets of gears between the countershaft and one of the other shafts, braking means for applying a braking force to the countershaft, means responsive to the speed of rotation of the countershaft to control the operation of the barking means comprising a control circuit, means actuated by the circuit to operate the braking means, first switch means in the circuit, means responsive to the speed of the countershaft to actuate the first switch means, and second switch means in the circuit for bypassing the first switch means.
 6. Transmission meChanism according to claim 5 including means responsive to the gearshifting mechanism of the transmission for actuating the second switch means to bypass the first switch means when a gear set is to be engaged in order to move the vehicle from a standstill position. 